Project 1: Project Summary/Abstract The Superfund program is responsible for protecting public health and the environment by cleaning up the nation's most contaminated land as well as responding to environmental emergencies. As stated in EPA's web material, Cleanup Optimization at Superfund Sites is a recognized part of that mission, the stated goal being, to improve remedy protectiveness, effectiveness, and cost efficiency at all phases of a cleanup process. Sediments and soils are commonly the dominant reservoirs of toxicants at Superfund sites, but human exposure to toxicants is not only direct; it can occur via food chains, or, commonly, via water as toxicants are gradually released from soils and aquatic sediments. This project will focus on two important toxicants, NDMA and PAHs, but will also provide insights and methodologies relevant to the general problem of detection, mapping, and movement of harmful species. To protect human health and design effective and cost-effective cleanup requires understanding what toxicants are present, how they are distributed, and by what routes they move through the environment and enter people. Gaining this understanding is usually a slow, difficult, and costly process, given the extent and spatial variability of toxicant distributions and the high cost and slow speed of chemical sampling and lab analysis. There is thus a great opportunity to improve remediation protectiveness, effectiveness, and cost efficiency by developing new and cost-effective in situ sensor technologies that can rapidly measure both toxicant concentrations in water and their exchange rates with contaminated sediments. These novel sensors promise to enable research with the potential to give rise to paradigm shifting understanding of the spatiotemporal dynamics of contaminants. Project 1 is thus both highly relevant to the Superfund mission, and directly responsive to the third mandate of SARA Section 311(a), Methods and technologies to detect hazardous substances in the environment. Project 1 will develop and test in situ sensors to measure the concentrations of toxicants in water, and serve as portable sensors by field personnel, as moored long-term sentinel sensors at fixed locations, and for toxicant mapping from operated or autonomous vehicles. Further reflecting the critical role of contaminated sediments play, Project 1 will develop in situ technology to expeditiously determine location-specific rates at which sediment-borne toxicants are released to their surface waters (i.e., benthic fluxes). This information will help improve estimates of human exposure and optimize remediation strategies. Strong community interaction will be supported by field-testing of new sensors in the Mystic River Watershed, including the tributary Malden River, currently facing severe scrutiny for its extensive sediment contamination and for its central role in environmental justice issues in Malden and Everett, MA. This project will also create training opportunities for students to design and test novel sensors, deploying sensors in real-world settings and on novel platforms (including an AUV built by MIT undergraduate student), and taking part in community environmental affairs.